This purpose of the study is to determine how the synthesis of the individual ribosomal proteins (r-proteins) of Esherichia coli is coordinated. Genes for specific r-proteins have been removed from their normal promoter and placed on a plasmid where they are under the control of the lactose operon. The consequences of induction of the r-protein genes now under lac control are investigated. We have obtained evidence for an operon specific control mechanism which can be activated by a single or a few proteins from the operon.